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Coues' cassia, Coves' cassia, desert senna

dwarf senna

Habit Herbs, perennial, to 0.7 m. Leaves slightly sclerophyllous, 2–10 cm, hairy; stipules persistent, to 1 mm wide; extrafloral nectaries between all leaflet pairs, stipitate; leaflet pairs 2–4, blades obovate to elliptic-obovate or oblong-elliptic, 10–38 × 5–19 mm. Herbs, perennial, to 0.2 m. Leaves slightly sclerophyllous, 1.5–10 cm, hairy; stipules persistent; extrafloral nectary between leaflet pair, highly reduced; leaflet pairs 1, blades lanceolate-acuminate or oblanceolate, 10–50 × 2–5 mm.
Racemes

(2–)4–8-flowered;

bracts caducous.

1-flowered;

bracts caducous.

Pedicels

8–17 mm.

6–21 mm.

Flowers

monosymmetric;

calyx pale green, pinkish, or yellowish;

corolla golden yellow, longest petal 9–15 mm;

androecium not heterantherous, stamens 7, staminodes 3;

anthers 2.5–4.2 mm, dehiscing by 1 apical pore, apical appendage 0;

gynoecium linear, slightly incurved, ovules 28–42;

ovary hairy;

style filiform, incurved.

monosymmetric;

calyx often persistent into developing fruit, pale green;

corolla pale yellow, longest petal 5.5–10 mm;

androecium not heterantherous, stamens 7, staminodes 3;

anthers to 2.9–4 mm, dehiscing by 1 apical pore, apical appendage 0;

gynoecium nearly linear, ovules 6–12;

ovary hairy;

style linear.

Legumes

erect, cylindrical, slightly curved, 180–350 × 50–80 mm, shallowly corrugated over seeds, dehiscing apically downward.

erect, cylindrical, straight, 8–15 × 6–8 mm, not corrugated over seeds, dehiscing apically downward.

Seeds

brown, rhomboid.

brown, paddle-shaped to pyriform.

2n

= 28.

Senna covesii

Senna pumilio

Phenology Flowering late winter–early fall. Flowering late winter–mid summer.
Habitat Sandy and gravelly desert washes, slopes, and stony hills, disturbed desert roadsides. Gravelly clay mounds and flats, sandy soils.
Elevation 0–1200 m. (0–3900 ft.) 50–2000 m. (200–6600 ft.)
Distribution
from FNA
AZ; CA; NM; NV; Mexico (Baja California, Sinaloa, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
TX; Mexico (Chihuahua, Coahuila, Durango, Nuevo León)
[BONAP county map]
Discussion

Senna pumilio is one of three sennas in North America forming and sprouting from a woody taproot (along with S. bauhinioides and S. ripleyana; H. S. Irwin and R. C. Barneby 1982).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Caesalpinioideae (excluding Mimosoid clade) > Senna Fabaceae > subfam. Caesalpinioideae (excluding Mimosoid clade) > Senna
Sibling taxa
S. alata, S. armata, S. artemisioides, S. atomaria, S. bauhinioides, S. corymbosa, S. durangensis, S. hebecarpa, S. hirsuta, S. ligustrina, S. lindheimeriana, S. marilandica, S. mexicana, S. multiglandulosa, S. obtusifolia, S. occidentalis, S. orcuttii, S. pendula, S. pilosior, S. pumilio, S. ripleyana, S. roemeriana, S. surattensis, S. wislizeni
S. alata, S. armata, S. artemisioides, S. atomaria, S. bauhinioides, S. corymbosa, S. covesii, S. durangensis, S. hebecarpa, S. hirsuta, S. ligustrina, S. lindheimeriana, S. marilandica, S. mexicana, S. multiglandulosa, S. obtusifolia, S. occidentalis, S. orcuttii, S. pendula, S. pilosior, S. ripleyana, S. roemeriana, S. surattensis, S. wislizeni
Synonyms Cassia covesii, Earleocassia covesii Cassia pumilio, Tharpia pumilio
Name authority (A. Gray) H. S. Irwin & Barneby: Phytologia 44: 499. (1979) (A. Gray) H. S. Irwin & Barneby: Phytologia 44: 500. (1979)
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